1. Field of the Invention
The invention concerns a binary output signal programmer.
2. Description of the prior art
Programmers are devices whose output signals control the operation of various equipment in a predefined sequence. This sequence is usually stored in the programmer itself and progress through the sequence is controlled by an external timing signal.
Prior art solutions to providing programmers producing a small number of output signals are summarized in the application EP 0 449 190, hereby incorporated by way of reference. This earlier application also proposes a solution that is well suited to larger numbers of output signals. The programmer produces g binary output signals in response to a timing signal identifying time intervals of duration T, each output signal starting and ending during separate time intervals. It comprises a memory having a start location assigned an address and an end location assigned an address for each output signal, read means for reading numerical values in these memory locations, control means determining the operation of the read means using an address generator so that all the memory locations are read during each time interval, comparator means producing an identity signal if a first field of a start or end location has the same value as a first field of the time interval, as indicated by a timing signal, in which the reading takes place, and decoder means producing or interrupting the output signal corresponding to the location for which the identity signal is produced according to whether that location is respectively a start location or an end location.
This means that during the time period T it is necessary to examine 2q situations, that is two situations for each output signal. The processing time available for each situation is thus t=T/2q. This processing time t cannot be made arbitrarily small. The processing time is limited by the technology of the programmer. Additionally, the implementation cost is directly proportional to the speed of the technology and the power consumption is also related to the required speed of operation.
It is therefore necessary to assume that for a given application, the processing time is a given. The result is that the number g of output signals and the duration T of a time interval cannot be set independently. It is then possible to define a performance factor which represents the performance of the programmer and which has the value q/T. In other words, it is the number of output signals that can be processed during time T.
An object of the present invention is to provide a binary output signal programmer having an enhanced performance factor so that a larger number of output signals can be processed for a given fixed duration T or so that the same number of output signals can be processed during a shorter time. That is to say the present invention provides improved temporal precision.